Allowed to overwrite resource id in serializer (#1127)

Co-authored-by: Oliver Sauder <os@esite.ch>

Author: axieum

AUTHORS

@@ -20,6 +20,7 @@ Jeppe Fihl-Pearson <jeppe@tenzer.dk>
 Jerel Unruh <mail@unruhdesigns.com>
 Jonas Kiefer <https://github.com/jokiefer>
 Jonas Metzener <jonas.metzener@adfinis.com>
+Jonathan Hiles <jonathan@hil.es>
 Jonathan Senecal <contact@jonathansenecal.com>
 Joseba Mendivil <git@jma.email>
 Kal <kal+oss@tedspot.com>

CHANGELOG.md

@@ -22,6 +22,23 @@ any parts of the framework not mentioned in the documentation should generally b
 * Replaced `OrderedDict` with `dict` which is also ordered since Python 3.7.
 * Compound document "include" parameter is only included in the OpenAPI schema if serializer
   implements `included_serializers`.
+* Allowed overwriting of resource id by defining an `id` field on the serializer.
+
+    Example:
+    ```python
+    class CustomIdSerializer(serializers.Serializer):
+        id = serializers.CharField(source='name')
+        body = serializers.CharField()
+    ```
+
+* Allowed overwriting resource id on resource related fields by creating custom `ResourceRelatedField`.
+
+    Example:
+    ```python
+    class CustomResourceRelatedField(relations.ResourceRelatedField):
+        def get_resource_id(self, value):
+            return value.name
+    ```
 
 ### Fixed
 

docs/usage.md

@@ -278,6 +278,44 @@ class MyModelSerializer(serializers.ModelSerializer):
     # ...
 ```
 
+### Overwriting the resource object's id
+
+Per default the primary key property `pk` on the instance is used as the resource identifier.
+
+It is possible to overwrite the resource id by defining an `id` field on the serializer like:
+
+```python
+class UserSerializer(serializers.ModelSerializer):
+    id = serializers.CharField(source='email')
+    name = serializers.CharField()
+
+    class Meta:
+        model = User
+```
+
+This also works on generic serializers.
+
+In case you also use a model as a resource related field make sure to overwrite `get_resource_id` by creating a custom `ResourceRelatedField` class:
+
+```python
+class UserResourceRelatedField(ResourceRelatedField):
+    def get_resource_id(self, value):
+        return value.email
+
+class GroupSerializer(serializers.ModelSerializer):
+    user = UserResourceRelatedField(queryset=User.objects)
+    name = serializers.CharField()
+
+    class Meta:
+        model = Group
+```
+
+<div class="warning">
+    <strong>Note:</strong>
+    When using different id than primary key, make sure that your view
+    manages it properly by overwriting `get_object`.
+</div>
+
 ### Setting resource identifier object type
 
 You may manually set resource identifier object type by using `resource_name` property on views, serializers, or

rest_framework_json_api/relations.py

@@ -247,17 +247,21 @@ def to_internal_value(self, data):
         return super().to_internal_value(data["id"])
 
     def to_representation(self, value):
-        if getattr(self, "pk_field", None) is not None:
-            pk = self.pk_field.to_representation(value.pk)
-        else:
-            pk = value.pk
-
+        pk = self.get_resource_id(value)
         resource_type = self.get_resource_type_from_included_serializer()
         if resource_type is None or not self._skip_polymorphic_optimization:
             resource_type = get_resource_type_from_instance(value)
 
         return {"type": resource_type, "id": str(pk)}
 
+    def get_resource_id(self, value):
+        """
+        Get resource id of related field.
+
+        Per default pk of value is returned.
+        """
+        return super().to_representation(value)
+
     def get_resource_type_from_included_serializer(self):
         """
         Check to see it this resource has a different resource_name when

rest_framework_json_api/renderers.py

@@ -443,10 +443,9 @@ def build_json_resource_obj(
         # Determine type from the instance if the underlying model is polymorphic
         if force_type_resolution:
             resource_name = utils.get_resource_type_from_instance(resource_instance)
-        resource_id = force_str(resource_instance.pk) if resource_instance else None
         resource_data = {
             "type": resource_name,
-            "id": resource_id,
+            "id": utils.get_resource_id(resource_instance, resource),
             "attributes": cls.extract_attributes(fields, resource),
         }
         relationships = cls.extract_relationships(fields, resource, resource_instance)

rest_framework_json_api/utils.py

@@ -304,6 +304,19 @@ def get_resource_type_from_serializer(serializer):
     )
 
 
+def get_resource_id(resource_instance, resource):
+    """Returns the resource identifier for a given instance (`id` takes priority over `pk`)."""
+    if resource and "id" in resource:
+        return resource["id"] and encoding.force_str(resource["id"]) or None
+    if resource_instance:
+        return (
+            hasattr(resource_instance, "pk")
+            and encoding.force_str(resource_instance.pk)
+            or None
+        )
+    return None
+
+
 def get_included_resources(request, serializer=None):
     """Build a list of included resources."""
     include_resources_param = request.query_params.get("include") if request else None

tests/test_relations.py

@@ -10,9 +10,10 @@
     HyperlinkedRelatedField,
     SerializerMethodHyperlinkedRelatedField,
 )
+from rest_framework_json_api.serializers import ModelSerializer, ResourceRelatedField
 from rest_framework_json_api.utils import format_link_segment
 from rest_framework_json_api.views import RelationshipView
-from tests.models import BasicModel
+from tests.models import BasicModel, ForeignKeySource, ForeignKeyTarget
 from tests.serializers import (
     ForeignKeySourceSerializer,
     ManyToManySourceReadOnlySerializer,
@@ -46,6 +47,28 @@ def test_serialize(
 
         assert serializer.data["target"] == expected
 
+    def test_get_resource_id(self, foreign_key_target):
+        class CustomResourceRelatedField(ResourceRelatedField):
+            def get_resource_id(self, value):
+                return value.name
+
+        class CustomPkFieldSerializer(ModelSerializer):
+            target = CustomResourceRelatedField(
+                queryset=ForeignKeyTarget.objects, pk_field="name"
+            )
+
+            class Meta:
+                model = ForeignKeySource
+                fields = ("target",)
+
+        serializer = CustomPkFieldSerializer(instance={"target": foreign_key_target})
+        expected = {
+            "type": "ForeignKeyTarget",
+            "id": "Target",
+        }
+
+        assert serializer.data["target"] == expected
+
     @pytest.mark.parametrize(
         "format_type,pluralize_type,resource_type",
         [

tests/test_utils.py

@@ -14,6 +14,7 @@
     format_resource_type,
     format_value,
     get_related_resource_type,
+    get_resource_id,
     get_resource_name,
     get_resource_type_from_serializer,
     undo_format_field_name,
@@ -392,6 +393,22 @@ class SerializerWithoutResourceName(serializers.Serializer):
     )
 
 
+@pytest.mark.parametrize(
+    "resource_instance, resource, expected",
+    [
+        (None, None, None),
+        (object(), {}, None),
+        (BasicModel(id=5), None, "5"),
+        (BasicModel(id=9), {}, "9"),
+        (None, {"id": 11}, "11"),
+        (object(), {"pk": 11}, None),
+        (BasicModel(id=6), {"id": 11}, "11"),
+    ],
+)
+def test_get_resource_id(resource_instance, resource, expected):
+    assert get_resource_id(resource_instance, resource) == expected
+
+
 @pytest.mark.parametrize(
     "message,pointer,response,result",
     [

tests/test_views.py

@@ -183,6 +183,50 @@ def test_patch(self, client):
             }
         }
 
+    @pytest.mark.urls(__name__)
+    def test_post_with_missing_id(self, client):
+        data = {
+            "data": {
+                "id": None,
+                "type": "custom",
+                "attributes": {"body": "hello"},
+            }
+        }
+
+        url = reverse("custom")
+
+        response = client.post(url, data=data)
+        assert response.status_code == status.HTTP_200_OK
+        assert response.json() == {
+            "data": {
+                "type": "custom",
+                "id": None,
+                "attributes": {"body": "hello"},
+            }
+        }
+
+    @pytest.mark.urls(__name__)
+    def test_patch_with_custom_id(self, client):
+        data = {
+            "data": {
+                "id": 2_193_102,
+                "type": "custom",
+                "attributes": {"body": "hello"},
+            }
+        }
+
+        url = reverse("custom-id")
+
+        response = client.patch(url, data=data)
+        assert response.status_code == status.HTTP_200_OK
+        assert response.json() == {
+            "data": {
+                "type": "custom",
+                "id": "2176ce",  # get_id() -> hex
+                "attributes": {"body": "hello"},
+            }
+        }
+
 
 # Routing setup
 
@@ -202,6 +246,14 @@ class CustomModelSerializer(serializers.Serializer):
     id = serializers.IntegerField()
 
 
+class CustomIdModelSerializer(serializers.Serializer):
+    id = serializers.SerializerMethodField()
+    body = serializers.CharField()
+
+    def get_id(self, obj):
+        return hex(obj.id)[2:]
+
+
 class CustomAPIView(APIView):
     parser_classes = [JSONParser]
     renderer_classes = [JSONRenderer]
@@ -211,11 +263,26 @@ def patch(self, request, *args, **kwargs):
         serializer = CustomModelSerializer(CustomModel(request.data))
         return Response(status=status.HTTP_200_OK, data=serializer.data)
 
+    def post(self, request, *args, **kwargs):
+        serializer = CustomModelSerializer(request.data)
+        return Response(status=status.HTTP_200_OK, data=serializer.data)
+
+
+class CustomIdAPIView(APIView):
+    parser_classes = [JSONParser]
+    renderer_classes = [JSONRenderer]
+    resource_name = "custom"
+
+    def patch(self, request, *args, **kwargs):
+        serializer = CustomIdModelSerializer(CustomModel(request.data))
+        return Response(status=status.HTTP_200_OK, data=serializer.data)
+
 
 router = SimpleRouter()
 router.register(r"basic_models", BasicModelViewSet, basename="basic-model")
 
 urlpatterns = [
     path("custom", CustomAPIView.as_view(), name="custom"),
+    path("custom-id", CustomIdAPIView.as_view(), name="custom-id"),
 ]
 urlpatterns += router.urls